The generation of electric power from thermal energy absorbed from solar radiation has been proposed as an alternative or complementary technological approach to the burning of fossil fuels, with societal benefits accruing from reduction in emissions from combustion, from reduced reliance on limited nonrenewable resources, and from the alleviation of political and ecological problems associated with the procurement and distribution of fossil fuels.
Efficient utilization of the solar radiation resource is deemed necessary if solar electric power plants are to approach cost effectiveness relative to fossil fuel combustion plants. Systems based on cylindrical parabolic trough mirrors such as those which were built in the Mojave Desert in California in the 1980s were financially successful because of governmental subsidies in the form of tax breaks and preferential electricity tariffs, but suffer from relatively low conversion efficiencies both because of the necessity to invest significant energy in the circulation of a synthetic oil used as the working fluid for heat absorption, and because of the relatively low thermodynamic efficiency of the Rankine cycle at the moderate maximum temperatures allowed by the synthetic oil. A solar thermal electric configuration with higher efficiency of solar-to-electric conversion has been proposed in the form of a central power tower system in which steam is generated and superheated in a central receiver by solar radiation reflected thereupon by fields of heliostats. This system overcomes the aforementioned deficiencies of the parabolic trough technology by foregoing an intermediate working fluid and obviating the need for energy-intensive circulation, as well as by producing steam at a higher temperature which yields a higher thermal efficiency in a Rankine cycle steam turbine. It has been further proposed to construct a central solar power tower system in which the working fluid is compressed air, where the solar-heated compressed air is later used in a Brayton cycle gas turbine in place of compressed air heated by combustion of a fuel, with the possibility of further improving the overall efficiency of the system by adding, for example, a heat recovery steam generator and a Rankine cycle steam turbine in a combined-cycle configuration. One problem encountered in the development of such a solar power tower system is the lack of availability of a solar receiver that can effectively heat a pressurized working fluid such as compressed air to the input temperature of a gas turbine, in the neighborhood of 1500° K.